16/17/18 - Diuretics Flashcards
Which DIURETIC?
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- *BUMETANIDE**
- *LOOP DIURETIC**
40-50x more potent than furosemide
Sulfonamide moiety
in furosemide and bumetanide also
provides weak CA inhibitory activity, thus
increase phosphate and bicarbonate excretion.
Which Diuretic causes this side effect?
“Contraction” Alkalosis
LOOP DIURETICS
Furosemide, Bumetanide, Torsemide, Ethacrinic Acid
Due to:
Significant diuresis can lead to hypovolemia ‐> stimulation of Aldosterone ‐> H+ excretion
Also:
HypoCalcemia*** // ***HypoMagnesemia
Ototoxicity // GOUT
Mild - HYPERglycemia / increase in Cholesterol / TG’s
Edema Treatment
Mainstay of therapy is:
NaCl RESTRICTION
diuretics will NOT work if the increased loss is REPLACED by MORE NACL INTAKE
Restriction depends on degree of edema:
SEVERE EDEMA: <1gm NaCl per day
- *Loop Diuretics are 1st line after**
- *daily dosing** –> increase dose or BID
Which DIURETIC?
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Dichlorfenamide
META-disulfamoylbenzene derivatives
Carbonic Anhydrase Inhibitor
Which DIURETIC?
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- *FUROSEMIDE**
- *LOOP DIURETIC**
Sulfonamide moiety
in furosemide and bumetanide also
provides weak CA inhibitory activity, thus
increase phosphate and bicarbonate excretion.
Which Diuretic?
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- *Acetazolamide**
- *SIMPLE heterocyclic sulfonamides**
Carbonic Anhydrase Inhibitor
Which Diuretic causes this side effect?
METABOLIC ACIDOSIS
CAIs
Acetazolamide + Methazolamide (Simple)
Dichlorfenamide + Dorzolamide (meta)
HCO3 is indirectly REABSORBED by CA
VVV
Blocking CA –> less HCO3 reabsorbed // more EXCRETED
VVV
METABOLIC ACIDOSIS
Which Diuretic causes this side effect?
HypoCalcemia
LOOP DIURETICS
•Furosemide, Bumetanide, Torsemide, Ethacrinic Acid
Also:
HypoKalemia // HypoMagnesemia
Ototoxicity // GOUT // Contaction ALKAlosis
Mild - HYPERglycemia / increase in Cholesterol / TG’s
Also used for:
Severe HYPERcalcemia
but MAINLY EDEMA
not proven to be good for HYPERtension
Which Diuretic causes this side effect?
HypoNatremia
THIAZIDE DIURETICS
Also:
HYPERcalcemia
HypoKalemia*** / ***HypoMagnesemia / GOUT
and MILD:
HyperGlycemia // TG // Cholesterol
INEFFECTIVE @ CrCl <30 mL/min
need RENAL function
What occurs in the ASCENDING LIMB?
Urine Formation
- *“Dilution of Luminal Fluid”**
- water IMpermeable*
RE-absorption of NaCl
30% of filtered Na+ –> reenters
Para-cellular Transport
used to compensate for HIGH Na+
- *Symporter_ + _Antiporter**
- *ATPase**
Which Diuretic is indicated for:
DECREASED MORTALITY**in**HFrEF
heart failure w/ reduced ejection fraction
Aldosterone Antagonist
Spironolactone & Eplerenone
K+ sparing Diuretics, weak diuretic
Other indications:
Combo w/ HCTZ to prevent hypokalemia
Hepatic Cirrhosis w/ ascites
Resistant Hypertension
2-Step Concentration Process
of
Renal Tubular Secretion
(1 of 2 ways to enter into the luminal fluid, Glomerular Filtration is the other)
@PROXIMAL TUBULE
1) Active Secretion, interstitium –> proximal tubule
via OATS / OCTS
most diuretics are either weak organic acids or weak organic bases
important for GOUT –> URIC ACID competes with DIURETICS
2) Passive + Active Transport, Proximal Tubule –> Luminal Fluid
of diuretics
Which DIURETIC?
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SORBITOL
Osmotic Diuretic
Which DIURETIC, based on MECHANISM OF ACTION?
- Inhibition of*
- *Renal Carbonic Anhydrase**
- decreases the:*
- *Sodium Carbonate Reabsorption**
Carbonic Anhydrase Inhibitors
CAI
Acetazolamide + Methazolamide
(Simple)
&
Dichlorfenamide + Dorzolamide
(meta)
Act on:
Proximal Tubule
Which DIURETIC?
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MANNITOL
Isomer of SORBITOL
Osmotic Diuretics
Which DIURETIC?
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- *TORSEMIDE**
- *Loop Diuretic**
- *sulfonylurea lacking an unsubstituted sulfamoyl group,**
- does not act at the proximal tubule*
- therefore does NOT increase phosphate or bicarbonate excretion.*
= no CA activity
Which Diuretic causes this side effect?
HYPERkalemia
K+ Sparing Diuretics
–Requires regular monitoring – can cause fatal arrhythmias
Risk increases greatly with CrCl < 50
Discontinue if K > 5.0 or CrCl < 30
Use in patients on dialysis is controversial in patients with HFrEF
Spironololactone also:
GYNECOMASTIA
What occurs in the COLLECTING DUCT?
Urine Formation
Re-Absorption of Water
- *Reabsorption & Secretion of**
- *Na / K / H / HCO3**
Na+/K+ ATPase
driving force for re-absprotion
- *What conditions cause a
- Diminished response to LOOP DIURETICS?***
Renal Insufficiency / Nephrotic Syndrome
Heart Failure / Cirrhosis
- may require
- HIGHER DOSES –> reach ceiling/max effect**
Ceiling dose:
- *80-160mg** for Furosemide
- *1-2 mg** for Bumetanide
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How does the nephron REACT to HYPOVOLEMIA?
Reduced Plasma Volume or Dehydration
↓Renal Blood flow
↓GFR
↑Renin Secretion
↑Antidiuretic Hormone
increase in water RE-absorption
Which DIURETIC?
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- *ETHCRYNIC ACID_ + _INDACRINONE**
- *Phenoxyacetic Acid-type High Ceiling Diuretics**
In addition to inhibit ATPase;
it also blocks the luminal Na+/K+/2Cl- co- transporter similar to furosemide
no sulfonamide group = does NOT inhibit CAI
Which DIURETIC?
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- *EPLERENONE**
- *K+ Sparing Diuretic**
Aldosterone Receptor Agonist
Eplerenone, a newer aldosterone receptor antagonist with better ADH receptor selectivity than spironolactone.
What can NOT be taken with a LOOP DIURETIC?
THIAZIDE DIURETICS
CAN NOT BE TAKEN WITH LOOP DIURETICS
What group on Thiazide Diuretics is associated with:
HyperSensitivity Rxns / Drug-Induced Fever
Blood Dyscrasias / Interstitial Nephritis
Cross Sensitivity with CAI’s
+ loop diuretics or antibiotics with this group
SULFAMOYL MOIETY
SO2NH2
Thiazide Diuretics also have ADR of:
HypoKalemia
Which DIURETIC acts on:
EARLY DISTAL TUBULE
THIAZIDE DIURETICS
Which DIURETIC acts on:
THICK ASCENDING LIMB
LOOP DIURETICS
Furosemide / Bumetanide / Torsemide
Which DIURETIC, based on MECHANISM OF ACTION?
Sodium and water reabsorption decreases
because of
reduced medullary hyper tonicity
and
elevated urinary flow rate
OSMOTIC DIURETIC
Mannitol / Isosorbide / Sorbitol
Act on:
Proximal Tubule
&
Descending Limb
Indication for these K+ Sparing Diuretics:
Sodium Channel Blockers
(of Collecting Ducts)
Triamterene / Amiloride
very weak diuretics
Often used in:
COMBO with HCTZ to PREVENT HypoKalemia
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Which DIURETIC, based on MECHANISM OF ACTION?
- INHIBITION OF*
- *Na+ - Cl- Symporter**
THIAZIDES + Thiazide -like
All Thiazides also have CA inhibition!
Act at the:
beginning of the DISTAL TUBULE
Which DIURETIC?
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- *Dorzolamide**
- *META-disulfamoylbenzene derivatives**
Carbonic Anhydrase Inhibitor
Benzothiazide (Thiazide) Diuretics
Which is ESSENTIAL FOR DIURETIC ACTIVITY?
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Sulfonamide** @ **C-7
is essential for diuretic Activity
EWG** @ **C-6
is needed for diuretic activity
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Benzothiazide (Thiazide) Diuretics
What can only TOLERATE a METHYL GROUP?
&
What can be REPLACED?
Carbonyl containing groups can replace the sulfonamide group at S-1 and N-2.
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N-2
can only tolerate a methyl group
will stop the THIAZIDE DIURETIC effect, but not CAI
Carbonyl-containing groups** –> **Sulfonamide
at S-1** & **N-2
can replace sulfonamide with no problem
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Which DIURETIC?
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- *AMILORIDE**
- *K+ Sparing Diuretic**
SELECTIVE SODIUM CHANNEL BLOCKER
Highly Basic
amiloride is excreted unchanged since it is not further metabolized
How do Thiazide Diurteics / Loop Diuretics cause
HypoKalemia?
In the Collecting Duct:
Increased Na+ Concentration in Urine
VV
Increased K+ Secretion into Urine
VVV
K+ Is released with the urine
“Na+ back IN –> K+ OUT”
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Which DIURETIC acts on:
LATE DISTAL TUBULE + COLLECTING DUCT
POTASSIUM SPARING DIURETICS
SPIRONOLACTONE
Aldosterone / Canrenone / Eplerenone
TRIAMTERENE & AMILORIDE
What occurs in the:
PROXIMAL TUBULE?
Urine Formation
REABSORPTION –> into blood
Glucose / Vitamins / AA / NaCl / HC03 / K / WATER
- *Transcellular Re-Absorption** by CA (carbonanhydrase)
- *Na+ / HCO3**
- passive processes:*
- *Transcellular Transport of**
- *Na+** coupled to Glucose / AA / Phosphate
- *PARAcellular Transport of**
- *Na+ / Cl-**
- through the INTERcellular space*
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Causes of Edema
Increased Capillary Hydraulic Pressure
due to liver or heart failure
HypoALBUMINemia
due to nephrotic syndrome / malnutrition
Increased Capillary Permeability
due to massive INFLAMMATORY states = burn patients
Lymphedema
lymphatic obstruction
Which DIURETIC?
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SPIRONOLACTONE –> Canerone
Canerone = major active metabolite
K+ Sparing Diuretic
ALDOSTERONE RECEPTOR AGONIST
synthetic steroid that blocks aldosterone receptors –> less Na+/K+ ATPase
in the later distal tubule and collecting duct
Indication for:
OSMOTIC DIURETICS
ELEVATED INTRACRANIAL PRESSURE
- *Given IV**
- does NOT penetrate BBB*
Once filtered, cannot be reabsorbed –> pulls fluid into tubules for excretion
Which Diuretic is Indicated for:
Prophylaxis of ACUTE ALTITUDE SICKNESS?
CAIs
Acetazolamide + Methazolamide (Simple)
Dichlorfenamide + Dorzolamide (meta)
Also for:
GLAUCOMA
Which Diuretic causes this side effect?
HYPERcalcemia
THIAZIDE DIURETICS
Also:
HypoNatremia
HypoKalemia*** / ***HypoMagnesemia / GOUT
and MILD:
HyperGlycemia // TG // Cholesterol
INEFFECTIVE @ CrCl <30 mL/min
need RENAL function
Which Loop Diuretic
does NOT have CA inhibitory Activity?
TORSEMIDE
does NOT have a
Sulfonamide Moiety
- does NOT increase
- Phos // Bicarb excretion**
Furosemide / Bumetanide does
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Phenoxyacetic Acid-Type
High Ceiling Diuretics
MoA / Target
Etacrynic Acid** + **Indacrinone
Target:
Thick Ascending Limb
Inhibits BOTH:
ATPase
Luminal Na/K/Cl- Co-Transporter
(similar to furosemide)
Which Diuretic causes this side effect?
GOUT
LOOP DIURETICS
Furosemide, Bumetanide, Torsemide, Ethacrinic Acid
THIAZIDE DIURETICS
Compete for elmination with:
OATs
VVV
ACCUMULATION OF URIC ACID
Which DIURETIC?
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Benzothiazide (Thiazide) Diuretics
What occurs in the DISTAL TUBULE?
Urine Formation
- *Secretion: Ammonia / Uric Acid / Penicillin**
- some WATER RE-absorption*
Symporter
Reabsorption of NaCl –> epithelium
Na+/ K+ ATPase
driving force for Re-absorption of Na –> Blood
Which Diuretic?
Indication:
Mainly as ANTI-HYPERTENSIVE, not as diuretic
CI:
INEFFECTIVE @ CrCl < 30 mL/min
Thiazide Diuretics
HCTZ / Chlorthalidone
Metolazone / Indapamide
Cause:
HypoNatremia
HypoKalemia // HypoMag
HYPERcalcemia / HYPERuricemia
Which DIURETIC, based on MECHANISM OF ACTION?
Inhibition of Na+ & Water RE-absorption by:
- *Competitive Inhibition of Aldosterone Receptor**
- *“MineralCorticoid Receptor”**
POTASSIUM SPARING DIURETIC
SPIRONOLACTIONE
Aldosterone / Canrenone / Eplerenone
Act on:
late DISTAL TUBULE + COLLECTING DUCT
Benzothiazide (Thiazide) Diuretics
- *What will:**
- *increase diuretic potency** and/or its duration of action?
- *What will:
- diminishes diuretic activity?***
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Substitution with a:
LIPOPHYLIC GROUP** @ **C-3
INCREASES diuretic potency +/- Duration of action
- any substitution of:*
- *Methyl Group_ @ _N-4_ / _C-5_ / _C-8**
- will DIMINISH diuretic activity*
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ADRs of Thiazides
HCTZ / Chlorthalidone
Metolazone / Indapamide
- HYPO*
- *K / Na** / Mg
HYPER
Calcium / Uricemia (Gout)
Glycemia / Cholesterol / LDL
What is Essential for CAI’s Inhibitory Activity
SAR?
- *UNSUBSTITUTED SULFAMOYL GROUP**
- *(SO2NH2)**
+attached to a+
Aromatic** or **Heterocyclic Ring
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Which DIURETIC, based on MECHANISM OF ACTION?
inhibition of the:
Luminal Na+ / K+ / 2Cl- Transporter System
**_LOOP_** or **High- Ceiling** MOST POTENT class of diuretics
Furosemide / Bumetanide / Torsemide
Act on:
THICK ASCENDING LIMB
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methylxanthines
Diuretic effect is due to ability to increase renal blood flow and glomerular filtration rate.
•Theophylline is most effective
Which DIURETIC acts on:
PROXIMAL TUBULE
CARBONIC ANHYDRASE INHIBITORS
Acetazolamide + Methazolamide
(Simple)
Dichlorfenamide + Dorzolamide
(meta)
OSMOTIC DIURETICS
Mannitol / Isosorbide / Sorbitol
also act on the DESCENDING LOOP
Which DIURETIC, based on MECHANISM OF ACTION?
Inhibition of Na+ & Water RE-absorption by:
Blockade of Na+ Channel @ Luminal Membrane
POTASSIUM SPARING DIURETIC
TRIAMTERENE & AMILORIDE
Act on:
Late DISTAL TUBULE & COLLECTING DUCT
Which Diuretic?
MoA:
Compete with WATER + CO2
for binding in the same active site
Of the Target Enzyme
- *CAI’s**
- *Carbonic Anhydrase**
Acetazolamide + Methazolamide
(Simple)
&
Dichlorfenamide + Dorzolamide
(meta)
Act on:
Proximal Tubule
What occurs in the
DESCENDING LIMB?
Urine Formation
“Concentration of Luminal Fluid”
Osmotic Water Diffusion + Salts (active)
- *WATER PERMEABLE**
- water is RE-ABSORBED here*
Small amount of Na is ABSORBED
active transport –> into URINE
Management of REFRACTORY EDEMA
ASSURE COMPIANCE
with Diuretic & NaCl Restriction
<1gm NaCl / day
- if ALL FAILS:*
- *Add Thiazide Diuretic**
- CAUTION –> PROFOUND DIURESIS / severe e- / volume depletion*
- only for SEVERE cases*
Which DIURETIC?
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Benzothiazide (Thiazide) Diuretics
The differences in
duration of action
are dictated mainly due to the
C-3 substituent.
Which DIURETIC?
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- *TRIAMTERENE**
- *K+ Sparing Diuretic**
SELECTIVE SODIUM CHANNEL BLOCKER
Highly Basic
Triamterene metabolizes extensively by the liver enzymes (due to the presence of the phenyl ring)
Which DIURETIC?
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Methazolamide
SIMPLE heterocyclic sulfonamides
Carbonic Anhydrase Inhibitor
What Diuretic is the only one that
DOES NOT ENTER THE TUBULAR LUMEN?
Aldosterone Antagonist
Spironolactone / Eplerenone
K+ Sparing Diuretic
Inhibit of the PRODUCTION of Na channels
VVV
reduce Na Reabsorption
Which diuretic has been shown to:
high quality of evidence for
reducing morbidity and mortality for hypertension
but is the least used
CHLORTHALIDONE
Thiazide Diuretic
HCTZ is still used the most
Metolazone and Indapamide
are generally only used with Loop Diuretics for synergy